Technical developments in high-field magnetic resonance imaging (MRI) and spectroscopy (MRS) have been accelerated because of the advantage of high sensitivity that significantly improves the capability and reliability for human applications. This advancement is further stimulated by the unique image contrasts available at high fields for fMRI and clinical diagnosis. However, to fully realize the advancement, many challenges must be resolved. Major problems associated with high fields are the difficulty of radiofrequency (RF) coil designs and the complex magnetic fields (B1) of RF coil when the wavelength of RF wave approaches RF coil's size. They result in (i) severe degradation of coil quality factor and NMR sensitivity, (ii) limitation for designing large size coils with high operating frequency and (iii) complex B1 field distributions and difficulty for quantifying MRI intensity. These complications necessitate innovative strategies to overcome the problems associated with RF coils at high fields. In collaboration with Dr. Yang from Penn State University, a comprehensive project is proposed in this grant application for addressing the RF engineering challenges at high fields. The major goals will focus on (i) developing a host of robust and efficient high-field RF coils for human and animal studies using an innovative design based on the microstrip transmission line (MTL) approach, (ii) studying the B1 field behavior in human head at high fields using computer simulation based on RF field modeling and MRI measurements, and studying the implications of B1 field on MRI quantification, (iii) conducting a series of study for systematically evaluating the proposed coils in comparison with other existing coils. Successful outcomes from this research will provide an alternative and satisfactory solution of RF coil design at high fields and result in significant technological advances in high-field RF coil engineering for in vivo MR applications.